"As a particle of the atmosphere is never lost, so sound is never lost. A strain of music or a simple tone will vibrate in the air forever and ever, decreasing according to a fixed ratio. The diffusion of the agitation extends in all directions, like the waves in a pool, but the ear is unable to detect beyond a certain point. It is well known that some individuals can distinguish sounds wich no others under precisely the same circumstances are wholly lost... A tone once in existence is always in existence."

Excerpt from SENSES OF VIBRATION [A History Of The Pleasure And Pain Of Sound] by Shelley Trower